1. Technical Field
Embodiments of the present invention relate to air-fuel control. More particularly, embodiments of the present invention relate to the air-fuel parameter control system, method and controller for compensating fuel film dynamics.
2. Description of Related Art
When a typical spark-ignition engine is operating, the toxic gases, such as CO, HC and Nox, are produced. The toxic gases can be converted to non-toxic gases by a three-way catalyst converter. When the air-fuel ratio reaches the stoichiometric air-fuel ratio, the catalyst conversion efficiency can be optimized, which minimizes the toxic gases. As a result, the air-fuel ratio not only affects the engine performance, but also affects the exhaust toxic gases. Therefore, air-fuel ratio control plays an important role in the engine management system.
The air-fuel ratio can be easily controlled to reach the stoichiometric air-fuel ratio when the engine operates in a steady state. However, when operation of the engine varies rapidly, such as quickly opening the throttle, the air-fuel ratio varies severely, which is unfavorable for reaching the stoichiometric air-fuel ratio.